Drying apparatus



y 1962 J. H. BREAKELL 'ETAL 3,045,358

DRYING APPARATUS- 2 Sheets-Sheet 1 Filed April 30, 1958 m K R MW k 0 D MIN: "D D D Ind \Q r m5 a l U. ww 8 km wm, MN 3 0 R 0 a n5 0Q 2Q \Q mm I RD 1 M /R n Qv 0 &Q\ N o 0 FL y 1962 J. H. BREAKELL ETAL 3,045,358

DRYING APPARATUS 2 Sheets-Sheet 2 Filed April 50, 1958 3,045,358 DRYING APPARATUS James H. Breakell, Philadelphia, and John E. Phillips,

hester, Pa., assignors to American Viscose Corporation, Philadelphia, Pa., a corporation of Delaware Filed Apr. 30, 1958, Ser. No. 732,038 11 Claims. (Cl. 341) The present invention relates to apparatus for drying moisture-laden packages, and particularly wound packages of filamentary material.

In the manufacture of artificial filaments, as for example of regenerated cellulose, liquid treating and drying of the filamentary material is accomplished while it is in the form of a wound annular package or cake having no central support. After undergoing various liquid treatments, the packages of filamentary material contain 30 to 40% moisture by weight (on the basis of the total weight of the package), and often as much as 60 to 80% by weight even after preliminary moisture extraction in a centrifuge. The conventional process of drying packages of filamentary material by heated gases is neither rapid nor efiicient. More important, this procedure results in the formation of a strained yarn in that the residual shrinkage in the dried yarn of the outer convolutions of the package is less than that of the dried inner windings of the package. An added disadvantage, is that yarn dried by this method has different dye absorption characteristics along its length, which depends upon the yarn position in the package during drying. This difference in dyeing may be recognized between cakes as Well as within the individual cakes themselves, and is frequently accompanied by a. barr effect in a finished fabric.

In view of the disadvantages of drying packages of filamentary material with heated gases, high frequency electric fields and particularly those in the radio frequency range, have been utilized as a drying medium. With this procedure, the packages travel between or along with at least one pair of spaced electrodes between which is provided a desired high frequency electric field. Drying is accomplished as the packages travel through an enclosed housing or chamber which is preferably circular in shape to facilitate a most satisfactory electrode placement, and which is provided with a small opening for package handling operations.

Control of the humidity and temperature conditions of the atmosphere within the chamber of known high frequency drying apparatus has not been satisfactory from the standpoint of minimizing or stopping objectionable condensation of steam within the drying chamber itself. The condensed droplets of moisture, are in effect, returned to packages undergoing drying and thus the resulting packages are non-uniformly dried. Repeated passes of the packages through the apparatus would, of course, deteriorate the yarn quality. Attempts to better control the drying chamber atmosphere by reducing the package handling opening provides the operator with an inadequate opportunity to load and unload the packages, and thus there is a likelihood that some packages may undergo more than one pass through the drying apparatus. Accordingly, it is a primary object of the present invention to provide a new or generally improved and more satisfactory drying apparatus Another object is to provide a package drying apparatus having a chamber within which atmospheric conditions are closely controlled to prevent vapor condensation.

Still another object is to provide, in a drying apparatus, an endless package conveyor having a pair of loop portions, one of which is positioned outside of the drying chamber and serves as a package loading and unloading section.

A further object is to provide, in a drying apparatus, a drying chamber having a package access opening covered with a continuous screen of heated air to prevent the entry of cool air.

A still further object is the provision of a high frequency electric dryer for packages of filamentary material in which a series of electrodes are disposed along an arcuate path and so supported as to avoid transfer of any condensed moisture from the electrodes to the filamentary packages.

These and other objects, features, and advantages, will become apparent from the following description of the invention and the drawing relating thereto in which:

FIGURE 1 is a perspective view of the apparatus of the present invention, with a portion thereof being broken away to illustrate the interior structure thereof; and

FIGURE 2 is a plan view of the structure shown in FIGURE 1, with the housing top wall being removed.

In general, the apparatus of the present invention is designed for removing moisture from packages of filamentary material as they travel between a series of spaced electrodes positioned within a drying chamber. The packages are carried into and through the drying chamber by an endless conveyor which has a first loop portion disposed outside of the drying chamber and serves as a package loading and unloading section, and a second loop portion positioned within the chamber itself. Control of the atmosphere within the drying chamber is achieved by heating means within the chamber combined with a vapor exhaust system. Assisting these atmosphere control means is a continuous screen of hot air spread across a package access opening in the chamber wall.

While the invention is described as being particularly useful for drying annular package of filamentary mate rial, it is not intended that the invention be limited to the treatment of filamentary materials or filaments made of a specific material. Further, the term moisture as used in the description includes all liquids and is not restricted to water.

With reference to the drawing, the apparatus of the present invention includes a framework 11 having a base plate 13, uprights 15, and struts or cross-braces 17. The wound packages of filamentary material, designated by the character 19, are carried through the desired drying cycle by article or package supports 21 which in turn are mounted on an endless roller chain conveyor 23. The conveyor 23 is trained over a sprocket 25 which is rotatably carried by the framework 11 and driven by suitable means, not shown. Preferably, a control is provided for the sprocket drive means to permit the conveyor to be selectively adjusted to a speed best suited for the material being treated, and the degree of drying desired.

The conveyor 23 is formed of a series of links 27 and 29 pivotally interconnected by pins 31. The pins 31 also serve as shafts for rollers 33 which ride between and along a pair of spaced channels 35 for guiding the conveyor along a desired circuitous path. Plates 36 are fixed to the conveyor links 27 and are provided with wear plates 37 which ride along the upper flanges of the channels 35 as the conveyor is advanced. The channels 35 are supported by the base plate 13 and include arcuate-shaped sections 38 and generally parallel arms 39 which terminate adjacent the sprocket 25. The channels 35' and sprocket 25 cause the conveyor 23 to travel along a closed path as best seen in FIGURE 2, and, in effect, shape the conveyor into two loop portions 41 and 43, the latter of which generally defines the drying area of the apparatu As more fully described hereafter, the loop portion 41 of the conveyor serves as a package loading and unloading section which is outside of the drying area of loop portion 43. The loop portion 41 of the conveyor 23 may be disposed in positions other than that illustrated, such as tangent to the loop portion 43 or along any plane between planes extending tangent and radially of the loop portion 43. Further, it will be noted that arms 39 of the channels 35 are preferably spaced relatively close to each other along the conveyor loop portion 41, thereby making opposite reaches of the conveyor 23 accessible to the operator for package handling functions. It will of course be understood that the shape of the conveyor loop portions 41 and 43 may be varied from an arcuate form without departing from the spirit and scope of the invention.

The article supports 21 are each suitably journalled on the conveyor links 27 for rotatable movement, and include a spindle 45 which projects into the space between the channels 35. A roller 47 is mounted on each of the spindles 45 and assists in guiding the conveyor 23 in much the same manner as the rollers 33 heretofore mentioned. Conventional means are provided between the spindles 45 and their respective journals to prevent movernent of the spindles in a vertical direction. A corrosion resistant plate or disc 49 is fixed to the upper end of each of the spindles 45 and is provided with posts 51 which support a perforated annular platform 53 on which the package 19 is supported. At the lower end of each of the spindles 45 is fixed a pinion gear 55 which in turn meshes with a rack or stationary link chain 56 to rotate the platform 53, and the package 19 carried thereon, as the conveyor 23 is advanced. Since package rotation is desired only during the drying cycle hereafter explained, the rack or chain 56 need not extend along the arms 39 of the channels 35. It will of course be understood that the speed of rotation of the platforms 53 may be varied as desired to obtain optimum drying results. As will be more apparent hereinafter, the perforations in the annular platforms 53 permit the circulation of convection currents through the platforms and provide for a more eflicient drying operation.

The posts 51 and platforms 53 are made from materials having a relatively low dielectric constant so as to minimize the absorption of electrical power therein during the drying operation. Ceramic materials have been found to be satisfactory for this purpose.

A housing 57, including an arcuate side wall 59 and top wall 61, cooperates with the base plate 13 to provide a chamber 62 within which package drying takes place. The housing may of course have a shape other than round, as illustrated. Supported by and projecting downwardly from the center of the housing top wall 61 is a conventional relatively high voltage radio frequency generator or oscillator, designated on the drawing at 63. The output circuit of the oscillator 63 preferably includes a series of electrodes 65 and 67 between which the filamentary packages 19 are carried by the conveyor 23. As illustrated, the electrodes are disposed vertically rather than horizontally to avoid any condensed moisture from falling onto the packages 19, and are arranged in a circular pattern for compactness and optimum electrode utilization. More specifically, the electrode 65 is connected by a suitable conductor 69 to the output terminal of the oscillator, whereas the electrode 67 is secured to the housing side wall at 70 and grounded by an annular-shaped bar 71 through metallic bands 73 which extend over the conveyor path.

The electrodes 65 and 67 are preferably formed of solid copper plates for the sake of ease and simplicity in fabrication. As shown in FIGURE 1, a duct 75 supplies cooling air to the oscillator 63 from a suitable source, not shown. To avoid corrosion problems, the various parts of the apparatus, other than the electrodes, are made of aluminum, while the electrodes themselves may be coated with a suitable protective material, such as Resistex, an epoxy-type material. If necessary, electrically heated drip pans may be provided below the metallic bands 73 to vaporize any moisture which may have condensed thereon.

The housing 57 is preferably releasably secured to the framework 11 and is suitably insulated to prevent heat loss by conduction, and vapor condensation along the inner wall surfaces. Removable panels 77 are provided in the housing side wall 59 to permit access into the housing without moving the housing itself. As a safety measure, the access panels 77 are electrically connected to an oscillator cut-out switch, not shown, to stop oscillator operation when the panels 77 are removed.

To remove vapors from the chamber 62, a suitable exhaust system is provided, such as a duct 81 disposed along the upper edge of the housing side wall 59 and having at least one outlet opening 83. The ends of duct 81 terminate adjacent to a package access opening 85 formed in the side wall 59 of the housing 57, with a header 87 connecting the ends of the duct 81 with an exhaust blower 89 fixed to the housing top wall 61. Coils 91 are positioned within the duct 81 and are connected by conduits 93 and 95 to a circulating flow of cooling fluid for condensing all or a major portion of the vapors exhausted from within the chamber 62. The duct 81 or the framework 11 is inclined so as to cause the condensed moisture to flow toward the ends of the duct 81, from which it is conveyed by drain tubes 96 to either a sewer or one of the conventional liquid treating baths used in the manufacture of filamentary material packages 19. Any suitable means, as for example a heat exchanger connected, between the conduits 93 and 95, may be used for chilling or supplying the fluid circulated through the coils 91.

During the drying operation, the atmosphere within the chamber 62 is maintained at approximately 212 F. by a series of steam heated tubes 99 which line the inner surface of the housing side wall 59 and the base plate 13. It will be noted that the placement of the heating tubes 99 further guards against steam condensation along the internal housing surfaces. If necessary, a drip pan may be provided along the base of the housing 57 to collect any moisture which condenses on the outer surface of the housing side wall 59.

As heretofore mentioned, one of the main problems of known package drying apparatus has been the condensation of steam within the drying chamber, which is caused primarily by a continuous flow of cool air through the package loading and unloading opening. To eliminate this objection, the apparatus of the present invention is provided with at least one header 101 disposed along the top of side edge or edges of the housing opening 85 and supplied with hot air from a suitable source. Nozzles 103 mounted on the header 101 discharge the heated air as a continuous protective curtain or screen across the housing opening 85. Thus, cool air drawn toward the housing opening is preheated by the screen of heated air before entry into the chamber 62. By preventing or at least minimizing the entry of cold air into the chamber 62, it will be further noted that heating of the atmosphere within the chamber 62 can be achieved more economically.

T 0 permit the removal of the housing 57, as for example for major repair of the oscillator 63 or conveyor 23, an overhead electrically operated traversing hoist 105 is provided. The hoist 105 is of conventional construction and rides along a track 107 suspended from fixed structure (not shown). Elevation and support of the housing during movement is achieved through a yoke 109 which engages with lifting rings 111 on the housing, and a cable 113 of the hoist 105. To facilitate the removal of the housing, all air, steam and cooling fluid conduits are provided with either detachable joints or flexible sections in the vicinity of the housing.

In using the apparatus of the present invention, the operator stands to one side of the conveyor 23 as it travels along the loop portion 41 of its path and places the annular filamentary packages 19 on the platforms 53 of the article supports 21 while alternately removing dried packages from the supports as they emerge from the housing. As heretofore mentioned, the opposite reaches of the conveyor loop portion 41 are both within the reach of the operator. Thus, in view of the large number of article supports which are available to the operator at the conveyor or loop portion 41, he can easily load, and

unload the packages 19 without being rushed. The continuous travel of the conveyor 23 carries the packages 19 through the curtain of hot air supplied by the header 101 and nozzles 103 and then between the circular pattern of spaced electrodes 65 and 67 which are energized through the oscillator 63. The voltage of the high frequency field between the electrodes 65 and 67 could vary anywhere from 3,000 to 25,000 volts and its frequency could range from one to 50 or more megacycles, it being understood that, in general, the higher voltage and frequency, the higher the rate of heat input and drying.

As the packages 19 enter the chamber 62, the pinion gears 55 of the article supports 21 mesh with the fixed chain or rack 56 to rotate the platforms 53 at the predetermined rate. During the drying cycle, the filamentary packages 19 gradually shrink and it will be noted that any protective fabric or sleeve on the package can droop freely into the annular opening in the package support disc 49 without blocking perforation in the platform 53.

Steam is continuously removed from the chamber 62 and condensed within the tube 81 by the cooling coils 91, while the atmosphere within the chamber 62 is maintained at a temperature of approximately 212 F. by the steam heated tubes 99. The fluid, as for example water, circulated through the coils 91 is at a temperature of about 130 F. as it enters the housing, and approximately at 160 F. as it leaves, and thereby absorbs the heat of evaporation for useful work elsewhere.

It will be noted that throughout the drying operation, complete control of the temperature and humidity of the atmosphere within the chamber 62 is maintained. Further, the novel conveyor arrangement permits package loading and unloading with ease and thus eliminates or minimizes the possibility that the packages will travel more than one pass through the drying area.

It is seen from the above description that the objects of the invention are well fulfilled by the structure described. The description is intended to be illustrative only and it is to be understood that changes and variations may be made without departing from the spirit and scope of the invention as defined by the appended claims.

We claim:

1. Apparatus for removing moisture from packages including a drying chamber, an opening in said chamber, means extending through said opening for carrying packages into, through and outwardly [Erom said chamber, means within said chamber for vaporizing moisture from the packages as they travel through said chamber, and means providing a screen of heated air across said opening to prevent the flow of cold air into said chamber.

2. Apparatus as defined in claim 1 wherein said means for carrying the packages includes an endless conveyor formed of a series of pivotally interconnected links, said conveyor having a first loop portion disposed outwardly of said chamber and serving as a package loading and unloading section and a second loop portion disposed within said chamber for carrying the packages therethrough.

5. Apparatus as defined in claim 2 wherein said second loop portion is larger in size than said first loop portion and extends along an are approaching a complete circle.

4. Apparatus as defined in claim 3 wherein said first loop portion extends along a plane disposed between planes extending tangent and radially of said second loop portion.

5. Apparatus as defined in claim 2 wherein said first loop portion is disposed along a plane which extends generally radially of said second loop portion.

6. Apparatus for removing moisture from packages of filamentary material including a drying chamber, an opening in said chamber, means extending through said opening for carrying packages into, through and outwardly from said chamber, means providing a screen of hot air across said opening to prevent the flow of cold air into said chamber, a pair of spaced electrodes disposed within said chamber along the path of said firstmentioned means, means for producing a high frequency electric field between said electrodes to vaporize moisture from the packages, means for rotating the packages as they travel between said electrodes, and means for removing vapors from within said chamber.

7. Apparatus :as defined in claim 6 further including means for heating the atmosphere said chamber.

8. Apparatus for removing moisture from packages of filamentary material including a drying chamber, an opening in said chamber, means for providing a screen of heated air across said opening to prevent the flow oi cold air into said chamber, an endless conveyor extending through said opening for carrying packages into, through and outwardly of said chamber, said conveyor iormed of a series of pivotally interconnected links and having a first loop portion disposed outwardly of said chamber and serving as a package loading and unloading section and a second loop portion disposed within said chamber, said second loop portion being larger in size than said first loop portion and having a configuration approaohing a closed loop, means along the path of the conveyor for advancing the same at a substantially uniform rate of speed, a pair of spaced electrodes disposed within said chamber along the path of said conveyor, means for producing a high voltage electric field between said electrodes to vaporize moisture from the packages, means for rotating the packages. as they travel between said electrodes, and means for removing vapors from within said chamber.

9. Apparatus as defined in claim 8 wherein said second loop portion extends along an arc of more than and less than 360.

10. Apparatus as defined in claim 9 wherein said first loop portion extends along a plane disposed between planes tangent and radial of said second loop portion.

11. Apparatus as defined in claim 9 wherein said first loop portion is disposed along a plane which extends generally radially of said second loop portion.

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